Recently, hardware (e.g., a digital camera and digital camcoder) which digitizes content data (e.g., moving image, still image, and audio data) by using an encoding technology for high compression rate, and records the digital data on a memory medium such as a memory card has come onto the market.
These hardware apparatuses often employ, as a video/audio digital encoding function, an encoding format which is high in compression efficiency, error resistance, and the like and can record data of a relatively long time by a limited resource.
Typical examples of the encoding format are MPEG-1, MPEG-2, and MPEG-4 which are standardized by ISO (International Organization for Standardization).
These hardware apparatuses can perform specialized playback such as fast-forward playback in a process of reading out and playing back encoded data recorded on a memory card or the like, particularly in a playback process for moving image data. At this time, only intra compression frames (to be referred to as I frames hereinafter) which can be decoded for each frame may be read out and displayed.
In general, the reading speed of a memory card varies depending on each product. In performing specialized playback, some memory cards are bottlenecked in the data reading speed of the memory card and cannot catch up with reading of I frames used for playback.
In this case, I frames are generally interlaced and played back at a predetermined interval in accordance with the speed of a product whose reading speed is the lowest among memory cards which may be used. Even the use of a memory card having a high reading speed provides only the same playback quality as that of a low-speed memory card.
Also when a plurality of storage devices are switched and used, the frame reading frequency is generally set in accordance with a storage device whose reading speed is the lowest. For this reason, even if the storage device is switched to one having a high reading speed, the quality of a playback image does not improve.